Scientists successfully generate haploid human embryonic stem cells
This new type of stem cells is able to undergo division and could have an important impact on human genetic and medical research.
In a collaborative effort, scientists from The Hebrew University of Jerusalem (Israel), Columbia University Medical Center (NY, USA) and The New York Stem Cell Foundation Research Institute (NY, USA), have succeeded in generating a new type of embryonic stem cell that carries a single copy of the human genome, instead of the two copies typically found in normal stem cells. The findings were recently published in Nature.
The stem cells described in the study are the first human cells that are known to be capable of cell division with just one copy of the parent cell's genome.
Human cells are considered 'diploid' because they inherit two sets of chromosomes, 23 from the mother and 23 from the father. The only exceptions are reproductive germ cells (egg and sperm), known as 'haploid' cells because they contain a single set of 23 chromosomes and cannot divide to make more eggs and sperm.
Previous efforts to generate embryonic stem cells using human egg cells have resulted in diploid stem cells. In this study however, the scientists induced cell division in unfertilized human egg cells and demonstrated that these haploid stem cells were pluripotent whilst retaining a single set of chromosomes.
The team was also able to demonstrate that by having just a single copy of a gene to target, haploid human cells may constitute a powerful tool for genetic screens in biomedical fields such as cancer research, precision and regenerative medicine.
"One of the greatest advantages of using haploid human cells is that it is much easier to edit their genes," explained Ido Sagi, research leader at the Azrieli Center for Stem Cells and Genetic Research. “In diploid cells, detecting the biological effects of a single-copy mutation is difficult, because the other copy is normal and serves as "backup."
The stem cells described in this study were a genetic match to the egg cell donor. This new type of stem cell could be used to develop cell-based therapies for diseases such as blindness, diabetes, or other conditions in which genetically identical cells offer a therapeutic advantage. Furthermore, the cells’ haploid state could result advantageous for developmental and reproductive studies.
"This study has given us a new type of human stem cell that will have an important impact on human genetic and medical research," stated Nissim Benvenisty, principal co-author of the study and Director of the Azrieli Center for Stem Cells and Genetic Research at the Hebrew University of Jerusalem. "These cells will provide researchers with a novel tool for improving our understanding of human development, and the reasons why we reproduce sexually, instead of from a single parent."
Ido Sagi, Gloryn Chia, Tamar Golan-Lev et al. Derivation and differentiation of haploid human embryonic stem cells. Nature. doi:10.1038/nature17408 (2016) (Online before print); http://www.alphagalileo.org/ViewItem.aspx?ItemId=162173&CultureCode=en